1. Field of the Invention
The present invention relates to a system for controlling data transmission and reception in a network.
2. Description of the Related Art
Generally, a communication network comprises a ring-type network, a bus-type network, and a number of stations. Each station has a ring-type network interface, a bus-type network interface, and a transmission-reception processing section connected between a ring-type network interface and a bus-type network interface. The data transferred from the bus-type network via the bus-type network interface is stored into the transmission buffer incorporated in the transmission-reception processing section. The source-address data (i.e., the data representing the address of the data source connected to the bus-type network) and the address data of the station are stored, as a set of data, into an address-changing table incorporated in the station.
The transmission-reception processing section searches the address changing table for destination-address data. When the destination-address data is not found in the table or is broadcast-address data, it is determined to be special station-address data. In this case, the transmission-reception processing section transmits data to all other stations at the same time. When the destination-address data is found in the address-changing table, the section transmits the data to only the station represented by the station-address data corresponding to the destination-address data. Until the section finishes transmitting this data, it cannot transmit any other data.
When data is supplied from the ring-type network to the transmission-reception processing section through the ring-type network interface, this data is stored into the reception buffer incorporated in the section. Destination-address data and station-address data included in this data are stored into the address-changing table. The transmission-reception processing section transmits the data stored in the reception buffer to the bus-type network through the bus-type network interface. Until the section finishes transmitting the data to the bus-type network, it can receive no data.
As has been pointed out, until the transmission-reception processing section completes the transmission of data from the ring-type network or the bus-type network which is connected to the ring-type network by the station, it cannot transmit any other data. The throughput in the communication network is reduced.
Accordingly, it is desirable that the throughput of the data transmission and reception between a ring-type network and a bus-type network is increased.